How would dry performance be compromised? What is the directional tire tread doing in the dry to improve traction? Because the email didn't specify in what situations the capabilities were going to be compromised.

You assume that email means all conditions. It could mean only wet/snow and the statement could be 100% correct.

We also don't have a copy of what that email is replying to.

 

Dave, you've made it clear over the past several years how you respect the capabilities of OE engineers. You've pointed out many times that it would be difficult to improve on a given OE engineer's design.

I find that viewpoint difficult to reconcile with your current observations on the tires. If a omnidirectional pattern were sufficient, why did the company spend the money to engineer a unidirectional tire? Certainly a omnidirectional tire would be more market friendly; it would appeal to buyer because of cheaper lifetime ownership and easier rotation.

I ask again: why a unidirectional tire? There must be some benefit baked into the design. Running them in reverse is compromising these qualities.

Do you see how your position on the tires is hard to reconcile with your other positions; i.e., the difficulty on improving on the design of the stock airbox(in which we are in agreement)?

 

Those questions would be better directed to Michelin. As you no doubt know tire technology is very complex with different compounds within a given tire, tread patterns, blocking, sipes, belts etc, etc. They are the ones saying "it will diminish the handling and handling characteristics the tire was designed to deliver." They also say "a unidirectional tire is designed to run in only one direction for maximum traction." You are quite right I assume this includes all conditions since there is no mention otherwise and it is implied by virtue of this. If you or others wish to assume for a directional tire that means only certain conditions and also want to speculate on which particular ones that is your choice.


The real intent of my post was to correct the statements attributed to Michelin and to offer my humble opinion which I have done. It is quite clear there is no mention of "may" or "certain conditions" in the email reply.

No we don't have the actual specific question although the answer appears to be quite straight forward and self explanatory. Are you trying to suggest otherwise and if so what?

 

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Trey said what I was going to say, you are getting the exact opposite effect that the tires were designed for. In this case saftey in the form of traction during wet weather. You now have, in effect, a tire designed specifically for decreasing traction in wet weather... crazy.

What you are implying is that directional tires are completely and laughably ineffective. The countless engineers at different companies on separate design teams have apparently designed, tested, and fully development their own versions of a universally accepted concept for performance directional tire design that is SO bad that if they designed it with the exact opposite goals in mind they would come up with basically the same product with the same safety and perfomance characteristics... crazy.

 

I don't see where I said that the unidirectional design of a tire is a farce. I've said more than once that the directional design helps channel out water and slush and by reversing the direction of the tire, the tire cannot channel the water out as effectively. I've also said that as a tire wears, it's poor weather capabilities become diminished and I think most of us are aware of that.

The advantages of a directional tire (non-asymetical) are this:

1) Improved water and slush channeling
2) Reduced cost to the manufactuer by way of the fact that the tread only has to be designed to run one way therefore they only have to focus on it's NVH and traction characteristics to run in one direction instead of having to compromise the design to allow it to run in both directions.

I have no doubt my reversed Avons are worse in standing water conditions, but I never drive at speeds in those conditions to come remotely close to the limits of the tire. I have already driven in very rainy conditions and the tires behave the same way they did. Would it be different if I was traveling at a higher rate of speed near the limitations of the tire of if the tires were new? Probably, but the same could be said for every significantly worn tire on the streets. Some people like to drive fast in the rain. I don't. Nearly 20 years of driving and I've never once lost it in the rain ON THE STREET and don't plan to either. I have lost control numerous times in my test lot, but that's because I'm doing very eratic manuvers to test how the car will behave and it's limitations in the wet. With that said, stability control is an amazing thing. It's shocking how well it works and it's also shocking just how easy it is to coax the tail out with the stability control off.

Like I stated before, the reversed tires are emitting fractionally more vibration than they did before. The steering wheel doesn't shake, but I can sense a little more graininess. You know how sensitive I am to changes in NVH. If the tires were new and I reversed them, then I'm pretty sure they'd also be noisier too. However, the tires are already half worn so naturally they'll be noisier and harsher.

All I know is this. Reversing a set of half worn and feathered 215/55R17 Avon M550s on my G resulted in this:

1) Eliminated tire roar
2) No perceptable change in steering response, feel, tracking
3) No obvious changes under extreme handling and braking manuvers
4) No obvious changes in heavy rain conditions
5) A slight increase in vibration felt though the steering wheel

 

Show me who exactly implied that about the tires Castro. It's not Dave as he has already mentioned decreased rain ability. Reading helps

 

Thanks for clearing that up Dave. I came to this thread late, so I'm sorry I missed anything you had already posted.

 

Here's one example:

"Grip in dry and wet (not standing water) conditions is largely dictated by the rubber compound used and the amount of rubber that meets the road, not the tread design."

Here's another good one:

"4) No obvious changes in heavy rain conditions"

But there were several others. Basically stating that it doesn't matter if you run it backwards in very wet conditions. Since it was designed specifically to channel water out and away from the tire at a high rate of speed, then running it backwards would channel water forward and into the tire's path, creating a potentially dangerous loss of traction. If this is not the case, which he stated several times, then one could conceivably presume that he is, by default, implying that the design is so rediculously ineffective that the exact oppostie design wouldn't change things. I disagree based on common sense, and could be wrong, but I still would never try it just to get a little more life out of some already worn out tires is all.

He did make this statement though:

"I have no doubt my reversed Avons are worse in standing water conditions, but I never drive at speeds in those conditions to come remotely close to the limits of the tire. I have already driven in very rainy conditions and the tires behave the same way they did. Would it be different if I was traveling at a higher rate of speed near the limitations of the tire of if the tires were new? Probably, but the same could be said for every significantly worn tire on the streets."

Which seems to clear up the issue and concede a little ground, but I would equate heavy rain with probably running into standing water at some point, admittedly a dangerous situation. It sounds like Dave is driving nice and slow anyway, but posting a potentially very dangerous solution to an annoyance isn't always such a good idea.

 

1st post

 

Touche! I see your point but still disagree with that first post. I don't think standing water is the only problem, I don't think you only have 10K miles on directional tires before they are useless, and bottom line I don't think running them backwards is safe or something to promote others to try. Agree to disagree I guess.

 

For anyone that's interested I have received an email back from Michelin. I asked some more specifics further to the reply that G35_Tx posted.

Sorry I didn't save my original online query to them and it wasn't included in their reply. From memory here is an abbreviated version of what I asked: It is generally accepted traction and handling is impaired in wet/sloppy road conditions for directional tires mounted in the reverse direction intended. Is dry traction and/or handling impaired by running a directional tire mounted in the reverse direction it was intended? Here is the response:

 

I'm surprised that you have had such a short life on the AVON's I have the same 550's in a 235/50/17 and they seem to hold up pretty well despite my moderately abusive habits.

 

RBull,

It's great you've asked the question directly Michelin and I respect their answer. The thing is though, I'm running Avon M550s which use the same rubber compound throughout the tire. I can't speak for Michelins tires because I don't own them. I do know what I feel and what I've observed by reversing the direction of my Avons. There is no perceivable difference in dry at the limit handling. Steering response, grip, stability, general feel, understeer, oversteer, etc. If my car/tires were exhibiting any sort of dangerous behavior, I would switch them back and note it in this post.

 

25-30K miles is about all I expect from these tires. That's pretty acceptable for a high performance all season tire.